With executive orders aimed at widening stem cell research and stripping ideology from scientific appointments, the president signals a clear departure from Bush.

WASHINGTON — President Obama made his most forceful break yet from his predecessor's controversial scientific agenda Monday, opening the door to a major expansion of government-funded research on embryonic stem cells and ordering federal agencies to strengthen the role of science in their decision-making.

The twin announcements marked a clear departure from former President George W. Bush's approach to science, which had caused a rift between that administration and a large segment of the nation's research community. Many complained that scientific data had been ignored or skewed as the Bush administration set policy on climate change, oil and gas drilling, and other aspects of environmental and health policy.

In particular, Bush's limits on federal funding for embryonic stem cell experiments had become a touchstone for many scientists angry at the administration, as well as for advocates for patients who have hoped the research would lead to cures for a wide range of diseases.

Obama, speaking to an audience of scientists and patients in the East Room of the White House, acknowledged that many people "strongly oppose" the research, which destroys human embryos, but that his choice was to "vigorously support scientists" in the field.

"The majority of Americans from across the political spectrum and from all backgrounds and beliefs have come to a consensus that we should pursue this research," the president said before signing an executive order lifting Bush's limits on the research. The order gives federal officials 120 days to issue new guidelines that will make a far wider range of experiments eligible for federal funding.

In addition, Obama signed a second executive order that he said was aimed at "restoring scientific integrity to government decision-making," a comment aimed sharply at Bush.

The order directs his administration to develop guidelines "to ensure that in this new administration we base our public policies on the soundest science, that we appoint scientific advisors based on their credentials and experience, not their politics or ideology."

"Today's action is about forcing taxpayers to fund ethically troublesome -- and unproven -- research that destroys life," Rep. Eric Cantor (R-Va.), the House Republican whip, said in a statement.

Cardinal Justin Rigali, chairman of a panel of the U.S. Conference of Catholic Bishops, called Obama's stem cell order "morally wrong, because it encourages the destruction of innocent human life, treating vulnerable human beings as mere products to be harvested. It also disregards the values of millions of American taxpayers who oppose research that requires taking human life."

The two executive orders align Obama with the scientists who had accused Bush of placing political concerns over scientific data in his environmental and healthcare policy-making. Many chafed at an administration they charged ignored crucial evidence about endangered species and scrubbed information from government reports of man-made global warming.

"They feel a breath of fresh air is blowing," said Tony Mazzaschi, interim chief science officer at the Assn. of American Medical Colleges, which represents many of the nation's leading research institutions.

In 2004, 60 prominent scientists accused the administration of "misrepresenting and suppressing scientific knowledge for political purposes."

Last fall, the Interior Department's inspector general issued a report detailing how one administrator intervened in at least 13 decisions under the Endangered Species Act.

The Bush administration angered others with its support for abstinence education despite evidence that such programs were unsuccessful in limiting teenage sexual activity.

Bush also made a number of highly controversial appointments to key scientific advisory panels. In one instance, he tapped a Christian activist who had called AIDS a "gay plague" to serve on the Presidential Advisory Council on HIV/AIDS. That move was unsuccessful.

The administration also was forced to backtrack in 2002 after a public outcry over a government website that discussed possible links between abortion and breast cancer. The National Cancer Institute updated its website to reflect the scientific consensus that there was no such link.

Still, Bush's policies had a chilling effect on many researchers, said Myron Genel, an emeritus professor at the Yale University School of Medicine and head of the Connecticut Academy of Science and Engineering.

"There was a strong sense that people who were very thoughtful who had different views were really precluded from being involved," he said.